Effects of Dietary Nitrate and Vitamin C Co-supplementation on Blood Pressure and Endothelial Function in Overweight Individuals

Effects of Dietary Nitrate and Vitamin C Co-supplementation on Blood Pressure and Endothelial Function in Overweight Individuals

The investigators have shown in two short-term studies in healthy, young participants that the combined supplementation of inorganic nitrate with vitamin C has beneficial effects on blood pressure and blood vessel wall stiffness. However, the effects of the combined supplementation have not been tested in individuals at greater cardiovascular disease risk. The investigators would like to show whether inorganic nitrate and vitamin C will produce greater effects on blood pressure and endothelial function when compared to inorganic nitrate alone versus the placebo treatment in people at greater risk of cardiovascular disease.

Inclusion Criteria:

• Participant is willing and able to give informed consent for participation in the study.
• Participant is willing and able to comply with the requirements of the study protocol.
• Non-smoking men and women.
• Aged between 50-75 years.
• Overweight and obese (BMI: over 25.0 kg/m2).

Exclusion Criteria:

• Having taken part in a research study in the last 3 months involving invasive procedures or an inconvenience allowance.
• Vegetarian.
• Smoking.
• Resting systolic blood pressure greater than 160 mmHg; diastolic blood pressure greater than 100 mmHg.
• Active cancer and any diagnosis of malignant cancer in the last 5 years.
• Excessive alcohol intake (>21 units per week).
• Allergy or intolerance to the intervention food (Beetroot juice).
• Diagnosis of chronic or acute metabolic and inflammatory conditions that may interfere with the study outcomes.
• Major surgical operations.
• Use of prescribed psychiatric drugs (antidepressants, sedatives, antipsychotics), diuretics, organic nitrates, statins and proton pump inhibitors.
• Use of prescribed hormonal therapies (oestrogens, thyroxin, and progesterone), anti-hypertensive (Calcium++ channel blockers, beta-blockers, and angiotensin-converting-enzyme (ACE) inhibitors), only if the prescription had started, or the dose had been started/changed, in the previous three months.
• Non-prescribed dietary supplements if not stopped at least for 2 weeks before starting the trial.
• Use of the mouthwash during the study was not allowed as it interferes with the conversion of oral nitrate into nitrite.